What you say sounds correct arithmetically. But practically, the train wont travel continuously for 110 kmph for 10 hours. We need to see the time spent by train above 100 per hour which will be less than 15 mins per hour. KR being single line, the train will have unscheduled halts, then scheduled halts, TSR/PSR... taken everything togather, there is hardly any time saving by giving a loco of 110.
Further, idont doubt the capacity of Diesel. They do the job perfectly, including Alco.